Electroconductive paper and carrier for electronic member using said paper

ABSTRACT

There are disclosed electroconductive paper which comprises on at least one side thereof, an electroconductive-substance-containing layer having a surface resistivity of at most 10 7  Ω and a surface pH in the range of 5.5 to 8.0, and which has preferably a half-life period of static electricity being at most 0.2 second and a concentration of sulfate ions of at most 1 ppm, the ions being extracted by subjecting 1 g of electroconductive paper to an extraction treatment in 70 milliliter (mL) of deionized water at 100° C. for 1 hour; and a carrier for an electronic member which carrier uses the electroconductive paper. The above electroconductive paper is capable of suppressing the corrosion of the electronic member due to the generation of sulfate ions and the like, and thereby is well suited for use as a carrier for the electronic member.

BACKGROUND OF THE INVENTION

[0001] 1 . Field of the Invention

[0002] The present invention relates to electroconductive paper, and inparticular to electroconductive paper which has anelectroconductive-substance-containing layer possessing a surfaceresistivity of a specific value or less and an almost neutral surface pHon at least one side thereof, and which is well suited for use as acarrier for an electronic member.

[0003] 2 . Description of the Related Arts

[0004] A fine electronic member has heretofore been supported on acarrier in the case of being transported or stored for the purpose ofpreventing individual electronic member from damaging each other, or ofenhancing the workability in a subsequent step. For instance, in thecase of a light-emitting diode having a metallic portion, transfer ofthe aforesaid diode is carried out by fastening a terminal of the metalportion to a narrow carrier in the form of tape by means of a hot meltadhesive or the like.

[0005] The characteristics required of such carrier include (1) to beelectroconductive for the purpose of preventing dust or the like fromadhering thereto or preventing the electronic member from beingelectrically damaged due to static electricity; (2) the surface pH ofthe carrier to be almost neutral in order that the metallic portion ofthe electronic member may not be corroded; (3). ions of a corrosiveimpurity, particularly sulfate ions are not to be generated in orderthat the metallic portion of the electronic member may not be corroded;and the like.

[0006] There have hitherto been employed as an electroconductivecarrier, a carrier made of plastics containing powdery electroconductivesubstance such as carbon black, fibrous electroconductive substance suchas carbon fibers and paper coated or incorporated inside with theabove-exemplified electroconductive substance. However, a carrier madeof plastics involves the problems of a fear of causing environmentalpollution in the incineration after its service, liability to moisturecondensation. On the other hand, a carrier made of paper, although beingless liable to moisture condensation and generation of staticelectricity as compared with the carrier made of plastics, involves theproblems of a fear of corroding the electronic member by a large amountof sulfate ions generated from the use of aluminum sulfate as a fixingagent or the use of an additive for paper making containing chemicals asa source of producing sulfate ions and the like.

SUMMARY OF THE INVENTION

[0007] In the light of the above-mentioned circumstances, a generalobject of the present invention is to provide electroconductive paperwhich is imparted with electroconductivity on at least one side thereof,and capable of suppressing the corrosion of the electronic member due tothe generation of sulfate ions or the like and at the same time, toprovide a carrier for the electronic member by using the above-mentionedelectroconductive paper.

[0008] Other objects of the present invention will become obvious fromthe text of this specification hereinafter disclosed.

[0009] As a result of intensive extensive research and investigationaccumulated by the present inventors in order to achieve the objects asmentioned before, it has been found that the objects can be achieved byelectroconductive paper which has anelectroconductive-substance-containing layer possessing a surfaceresistivity of a specific value or less and an almost neutral surface pHon at least one side thereof. The present invention has beenaccomplished by the above-mentioned findings and information.

[0010] Specifically, the present invention provides the followings.

[0011] 1. Electroconductive paper which comprises on at least one sidethereof, an electroconductive substance-containing layer having asurface resistivity of at most 10⁷ Ω and a surface pH in the range of5.5 to 8.0.

[0012] 2. The electroconductive paper as set forth in the preceding item1, which has a half-life period of static electricity being at most 0.2second.

[0013] 3. The electroconductive paper as set forth in the preceding item1 or 2, wherein the concentration of sulfate ions thereof is at most 1ppm, which are extracted by subjecting 1 g of electroconductive paper toan extraction treatment in 70 milliliter (mL) of deionized water at 100°C. for 1 hour.

[0014] 4. A carrier for the electronic member which carrier makes use ofthe electroconductive paper as set forth in the preceding item 1, 2 or3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The electroconductive paper according to the present inventionneeds to comprise on at least one side thereof, anelectroconductive-substance-containing layer. The constitution thereofis not specifically limited, but is exemplified by monolayer ormulti-layer electroconductive paper composed only of a layer or layerseach containing an electroconductive substance; double-layeredelectroconductive paper composed of a layer containing anelectroconductive substance and a layer not containing the same;triple-layered electroconductive paper composed of a layer notcontaining an electroconductive substance and on both the sides thereof,two layers each containing the same; and the like.

[0016] The layer containing an electroconductive substance and the layernot containing the same each constituting the electroconductive paperaccording to the present invention is made of paper manufactured by aconventional sheet making process.

[0017] As fibers for raw material of paper to be used in the presentinvention, there are cited natural pulp and synthetic pulp, variousfibers and the like to be used in combination with the natural pulp asdesired. The above-mentioned natural pulp is not specifically limited,but may be optionally selected for use from wood pulp, non-wood pulpsuch as basi fiber ganpi fiber.

[0018] In addition, examples of usable kinds of pulp include mechanicalpulp such as ground wood pulp which is obtained by mechanically treatinga raw material; chemical pulp which is obtained by treating a rawmaterial with a chemical agent such as sulfite pulp, soda pulp, sulfatepulp (kraft pulp), nitrate pulp and chlorine pulp; semi-chemical pulpwhich is obtained by chemical treatment and mechanical treatment incombination; bleached pulp which is obtained by subjecting any of theforegoing pulp to bleaching refining treatment; unbleached pulp which isnot subjected bleaching refining treatment; semi-bleached pulp which isintermediate between bleached pulp and unbleached; and the like pulp. Ofthese are preferable needle-leaved tree bleached kraft pulp (N-BKP),broad-leaved tree bleached kraft pulp (L-BKP) and a mixture thereof.Reclaimed waste pulp is also usable.

[0019] Examples of synthetic pulp to be used when desired includesynthetic pulp obtained from such material as polyethylene andpolypropylene. Examples of various fiber include organic fiber such asacrylic fiber, rayon fiber, phenolic resin fiber, polyamide base fiber,polyester base fiber and polyolefin base fiber and inorganic fiber suchas glass fiber and alumina fiber.

[0020] As the electroconductive substance to be used in the presentinvention, mention is made of powdery carbonaceous electroconductivesubstance such as carbon black and graphite electroconductive powderymetal oxide such as tin oxide, titanium oxide and zinc oxide; metalfiber such as copper, nickel and zinc; electroconductive fiber coated bymetal vapor deposition; carbon fiber; organic electroconductive highmolecular compounds such as polythiazine, halogenated polyacetylene,poly-p-phenylene, and the like. The above-cited electroconductivesubstances are preferably in the form of fiber rather than powder inorder to prevent dust generation.

[0021] Any of these electroconductive substance may be used alone or incombination with at least one other. The amount thereof to be blended isselected usually in the range of 1 to 100 parts by weight based on 100parts by weight of the above-mentioned fiber for raw material of paper.The amount thereof, when being less than 1 part by weight based on thesame, gives rise to insufficient electroconductivity, whereas theamount, when being more than 100 parts by weight based on the same,results in failure to exhibit the working effect on enhancingelectroconductivity considering the amount and rather leads to the causefor deteriorating the physical properties as electroconductive paper.For this reason, the amount to be blended is in the range of preferably1 to 50 parts by weight, particularly preferably 5 to 20 parts by weightbased on the same.

[0022] In the electroconductive paper according to the presentinvention, the electroconductive-substance-containing layer has asurface resistivity of at most 10⁷ Ω . The surface resistivity, whenbeing in more than 10⁷ Ω , gives rise to insufficientelectroconductivity, thereby brings about unsuccess in sufficientlyexerting the function of preventing dust or the like from adhering thepaper surface or preventing the electronic member from beingelectrically damaged due to static electricity, whereby the objects ofthe present invention are not achieved. The surface resistivity thereofis preferably at most 10⁵ Ω. The lower limit thereof is not restrictedin particular, but is usually 10¹ Ω, approximately. The measuring methodfor the surface resistivity will be described hereinafter.

[0023] The surface pH of the electroconductive-substance-containinglayer is in the range of 5.5 to 8.0. The surface pH thereof, when beingless than 5.5, causes corrosion of the metallic portion of theelectronic member, whereby the objects of the present invention are notachieved. On the other hand, the surface pH thereof, when being morethan 8.0, sometimes brings about corrosion of terminals of theelectronic member depending upon the raw material thereof, or exertsadverse influence up on the performance of the electronic member. Themeasuring method for the surface pH will be described hereinafter.

[0024] The half-life period of static electricity of theelectroconductive paper according to the present invention is preferablyat most 0.2 second. The half-life period thereof, when being more than0.2 second, will cause insufficiency in preventing charge-up due tostatic electricity, thereby gives rise to a fear of unsuccess insufficiently exerting the function of preventing dust or the like fromadhering the surface or preventing the electronic member from beingelectrically damaged due to static electricity. The lower limit thereofis not restricted in particular, but is usually 0.01 second,approximately. The measuring method for the half-life period of staticelectricity will be described hereinafter.

[0025] In addition, the concentration of sulfate ions of theelectroconductive paper according to the present invention is preferablyat most 1 ppm, which are extracted by subjecting 1 g ofelectroconductive paper to an extraction treatment in 70 milliliter (mL)of deionized water at 100° C. for 1 hour. When the concentration ofsulfate ions thereof is more than 1 ppm, the oxide film on the surfaceof metallic terminals is liable to be attacked, thereby unfavorablyincreasing the corrosion rate. The measuring method for theconcentration of sulfate ions will be described hereinafter.

[0026] The electroconductive paper in which the surface pH andconcentration of sulfate ions are each within the above-described rangecan be produced by neutralized paper making. By the term neutralizedpaper making as used herein is meant sizing treatment without the use ofaluminum sulfate or neutralization by chemical treatment at the time ofpaper making.

[0027] The electroconductive paper having such properties according tothe present invention is well suited for use as a carrier for theelectronic member.

[0028] The electroconductive-substance-containing layer in theelectrocondIuctive paper according to the present invention can beproduced by preparing aqueous suspension containing the above-mentionedfiber for raw material of paper and electroconductive substance each ata prescribed proportion, and subjecting the resultant suspension topaper making by a conventional well known method.

[0029] The aforesaid aqueous suspension may be properly optionallyincorporated when desired with any of a variety of neutral additives forpaper making which have heretofore been used for paper making such asfixing agent, wet paper strengthening agent, dry paper strengtheningagent, sizing agent and filler. It is preferable in the presentinvention to prevent the use of the additives for paper making whichcontain a compound that comes to be a source of generating sulfate ionsfrom the resultant electroconductive paper.

[0030] As the aforesaid fixing agent, mention is made ofpolyethylene-imine resin, a derivative thereof, polyacrylamide resin,polyamine resin, acrylic resin, polyamide resin, polyethylene oxideresin, polyamide/polyamine resin, a derivative thereof, basicpolyaluminum chloride, basic polyaluminum hydroxide and alumina sol.

[0031] As the aforesaid wet, paper strengthening agent, mention is madeof epoxidized polyamide resin, polyamide resin, epoxy resin, melamineresin, melamine/formalin resin and urea/formalin resin.

[0032] As the aforesaid dry paper strengthening agent, mention is madeof acrylic resin, polyamine resin, polyacrylamide resin, oxidizedstarch, carboxylated starch, cationized starch, vegetable gum, polyvinylalcohol resin and carboxymethyl cellulose .

[0033] As the aforesaid sizing agent, mention is made of at least onespecies selected from sizing agents such as alkyl ketene dimer, alkenylmaleic anhydride, polystyrene base resin and higher fatty acid baseresin.

[0034] As the aforesaid filler, mention is made of mineral base fillerssuch as talc, kaolin, calcined kaolin, clay, diatomaceous earth, groundcalcium carbonate, magnesium, carbonate, aluminuim hydroxide, titaniumdioxide, silica, aluminosilicate and bentonite, organic base fillerssuch as polystyrene grains and urea/formalin resin grains.

[0035] The aforesaid aqueous suspension may be properly optionallyincorporated when desired with an additive aid for paper making such asdyestuff, slime controlling agent, antifoaming agent and thickeningagent.

[0036] In the present invention, a sheet containing an electroconductivesubstance is prepared by carrying out paper making by the use of theaqueous suspension which comprises fiber as raw material of paper, anelectroconductive substance and any of a variety of additives to be usedwhen desired and which is prepared in the above-mentioned manner, sothat. monolayer electroconductive paper is obtained. On the other handin the case where the electroconductive paper according to the presentinvention contains a layer which is free from an electroconductivesubstance, a sheet free from an electroconductive substance is preparedby carrying out paper making by the use of the aqueous suspension whichcomprises fibers as raw material of paper and any of a variety ofadditives to be used when desired and which is prepared in the samemanner as above except that the aqueous suspension is free from anelectroconductive substance. Subsequently, the above-prepared sheetcontaining an electroconductive substance and the sheet free from anelectroconductive substance are together subjected to paper making, sothat electroconductive paper having double-layer or triple-layerstructure is obtained.

[0037] It is possible to coat or impregnate the surfaces of theelectroconductive paper according to the present invention obtained inthe foregoing manner with a surface strengthening agent such a oxidizedstarch, polyvinyl alcohol, surface sizing agent, pigment and any ofvarious high molecular compounds during or after a paper making step bya coating method using a size press, gate roll, air knife or blade roll.

[0038] In the electroconductive paper according to the presentinvention, there are usable the above-cited additives for paper making,additive aids for paper making and coating/impregnating chemical agents,each being anionic, cationic, nonionic or amphoteric. However asmentioned hereinabove, it is preferable not to use the additives,additive aids and chemical agents containing a compound that comes to bea source of generating sulfate ions in order to suppress theconcentration of sulfate ions to at most 1 ppm, which are extracted bysubjecting 1 g of electroconductive paper to an extraction treatment in70 mL of deionized water at 100° C. for 1 hour. As the additives,additive aids and chemical agents containing a compound that comes to bea source of generating sulfate ions, mention is made, for instance, ofemulsion solutions dispersed with an anionic emulsifier containing asulfate such as aluminum sulfate, basic aluminum sulfate, ferroussulfate, sulfonates and ester salts of ether sulfuric acid.

[0039] A proper basis weight of the electroconductive paper according tothe present invention is in the range of 64 to 600 g/m² (total basisweight of all layers for a plurality of layers), preferably 200 to 500g/m².

[0040] In summarizing the working effects and advantages of the presentinvention, it is possible to provide electroconductive paper which isimparted with electroconductivity on at least one side thereof andcapable of suppressing the corrosion of the electronic member due to thegeneration of sulfate ions and the like and at the same time, to providea carrier for the electronic member using the aforesaidelectroconductive paper.

[0041] In the following, the present invention will be described in moredetail with reference to comparative examples and working examples,which however shall never limit the present invention thereto. Thephysical properties of the electroconductive paper obtained in theexamples were determined by the procedures as described hereunder.

[0042] (1) Surface pH

[0043] Surface pH was determined in accordance with JAPAN TAPPI 1-1 A.

[0044] (2) Surface Resistivity Ω

[0045] Surface resistivity Ω was determined by a method in which boththe ends of electroconductive paper measuring 210 mm by 210 mm in sizein the machine direction (direction of paper parallel to the advancedirection of a paper machine) were sandwiched with clips each made ofstainless steel with 145 mm wide so that the distance therebetween wasset on 200 mm, each of the clips was brought into contact with anelectrode of a tester (available from TMK Co. Ltd. under the trade name“Multitester-VF-10”), and the indicated value at that time was regardedas the surface resistivity.

[0046] (3) Amount of Extracted Sulfate Ions

[0047] 1 g of electroconductive paper sample was immersed in 70 mL ofdeionized water so as to carry out extraction at 100° C. for 1 hour, anda measurement was made of the sulfate ions (ppm) in the resultantextract, wherein the deionized water was defined as having a volumespecific resistance of at least 15 k Ω·cm (25° C.). At that time, inorder to prevent the hand from coming in direct contact with theelectroconductive paper, use was made of double-layered cotton glovescovered with outer gloves made of polyethylene.

[0048] The measurement of extracted sulfate ions was carried out bymeans of ion chromatography (available, from Japan Dionex Co. Ltd. underthe trade name “DX320”) using as the standard sulfate ion solution, thesolution of 1,000 g of K₂ SO₄ dissolved in 1 liter of deionized water.The ion extraction vessel used therein was a vessel which was equippedwith a hermetically sealing lid and made of polypropylene, wherein theimpurity level in the vessel was limited to at most one fifth of apossible impurity level at the time of measuring the electroconductivepaper sample.

[0049] (4) Half-life Period of Static Electricity

[0050] Half-life period of static electricity was determined by the useof a static neostometer (available from Shishido Shokai Japan Co. Ltd.)at a temperature of 23° C. at a relative humidity of 50% and at anapplied voltage of 10 kV.

[0051] (5) Corrosion Test for Carrier

[0052] Corrosion test for carrier was carried out by a corrosionaccelerating test under the conditions including a temperature of 60° C.and a relative humidity of 90% for 10 days by sandwiching a terminalportion of a copper-made light emitting diode the terminal of which wasplated with silver with carriers in which electroconductive paper wasused, and then change in color, if any, was visually observed.

EXAMPLE 1

[0053] A sheet was prepared from a paper material prepared by adding to100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 10 parts by weight expressed in terms of solid content, ofcarbon pigment (available from Mikuni Pigment Co. Ltd. under the tradename “Grand Black AM-1000”) as the electroconductive substance; 0.05part by weight expressed in terms of solid content, ofpolyethylene-imine resin (available from Nippon Shokubai Kagaku KogyoCo. Ltd. under the trade name “Epomin P-1000”) as the fixing agent; 0.5part by weight expressed in terms of solid content, of epoxidizedpolyamide resin (available from Japan PMC Co. Ltd. under the trade name“WS-570”) as the wet paper strengthening agent; and 0.5 part by weightexpressed in terms of solid content, of polystyrene resin (availablefrom Seiko Chemical Industries Co. Ltd. under the trade name “Pearl GumCS”) as the sizing agent. The resultant sheet was coated on both sidesthereof in an amount of 3 g/m² expressed in terms of solid content withoxidized starch (available from Oji Corn Starch Co. Ltd. under the tradename “Oji Ace A”) as the surface strengthening agent at the time ofpaper making with a size press coater. As a result, there was obtainedelectroconductive paper which had a basis weight of 300 g/m², and thephysical properties of which are given in Table 1.

EXAMPLE 2

[0054] A sheet was prepared from a paper material prepared by adding to100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 5 parts by weight of carbon fiber (available from Toho TenacsCo. Ltd. under the trade name “Besfite Ae” cut into a size of 3 mm) asthe electroconductive substance; 0.5 part by weight expressed in termsof solid content, of epoxidized polyamide resin (available from JapanPMC Co. Ltd. under the trade name “WS-570”) as the wet paperstrengthening agent; and 0.5 part by weight expressed in terms of solidcontent, of polystyrene resin (available from Seiko Chemical IndustriesCo. Ltd. under the trade name “Pearl Gum CS”) as the sizing agent.

[0055] As a result, there was obtained electroconductive paper which hada basis weight of 300 g/m², and the physical properties of which aregiven in Table 1.

EXAMPLE 3

[0056] By the use of a paper machine for double-layer paper making whichwas equipped with Fourdrinier wire and a cylinder mould, double-layerpaper making was carried out to produce electroconductive paper composedof two layers consisting of a layer free from an electroconductivesubstance and a layer containing an electroconductive substance.

[0057] A paper material for the Fourdrinier wire was prepared by addingto 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 0.5 part by weight expressed in terms of solid content, ofepoxidized polyamide resin (available from Japan PMC Co. Ltd. under thetrade name “WS-570”) as the wet paper strengthening agent; 0.5 part byweight expressed in terms of solid content, of polystyrene resin(available from Seiko Chemical Industries Co. Ltd. under the trade name“Pearl Gum CS”) as the sizing agent; and 0.5 part by weight expressed interms of solid content, of acrylic resin (available from ArakawaChemical Industries Co. Ltd. under the trade name “Polystoron 191”) asthe dry paper strengthening agent.

[0058] On the other hand, a paper material for the cylinder mould wasprepared by using the materials same as in Example 1.

[0059] The resultant paper was coated on both sides thereof in an amountof 3 g/m² expressed in terms of solid content with oxidized starch(available from Oji Corn Starch Co. Ltd. under the trade name “Oji AceA”) as the surface strengthening agent at the time of paper making witha size press coater. As a result, there was obtained electroconductivepaper which was composed of two layers and had a basis weight of 400g/m² in which the Fourdrinier wire side had a basis weight of 350 g/m²,and the cylinder mould side had a basis weight of 50 g/m². The physicalproperties of the resultant electroconductive paper are given in Table1.

COMPARATIVE EXAMPLE 1

[0060] A sheet was prepared from a paper material prepared by adding to100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 10 parts by weight expressed in terms of solid content, ofcarbon pigment (available from Mikuni Pigment Co. Ltd. under the tradename “Grand Black AM-1000”) as the electroconductive substance; 0.5 partby weight expressed in terms of solid content, of rosin size (availablefrom Arakawa Chemical Industries Co. Ltd. under the trade name “SizepineE-50”) as the sizinig agent; 1 part by weight expressed in terms ofsolid content, of aluminum sulfate (available from Sumitomo Aluminum Co.Ltd. under the trade name “Aluminum sulfate”); and 0.5 part by weightexpressed in terms of solid content, of epoxidized polyamide resin(available from Japan PMC Co. Ltd. under the trade name “WS-570”) as thewet paper strengthening agent. The resultant paper material was coatedon both sides thereof in an amount of 3 g/m² expressed in terms of solidcontent with oxidized starch (available from Oji Corn Starch Co. Ltd.under the trade name “Oji Ace A”) as the surface strengthening agent atthe time of paper making with a size press coater. As a result, therewas obtained electroconductive paper which had a basis weight of 300g/m², and the physical properties of which are given in Table 1.

COMPARATIVE EXAMPLE 2

[0061] A sheet was prepared from a paper material prepared by adding to100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 10 parts by weight expressed in terms of solid content, ofcarbon pigment (available from Mikuni Pigment Co. Ltd. under the tradename “Grand Black AM-1000”) as the electroconductive substance; 0.05part by weight expressed in terms of solid content, ofpolyethylene-imine resin (available from Nippon Shokubai Kagaku KogyoCo. Ltd. under the trade name “Epomin P-1000”) as the fixing agent; 0.5part by weight expressed in terms of solid content, of epoxidizedpolyamide resin (available from Japan PMC Co. Ltd. under the trade name“WS-570”) as the wet paper strengthening agent. The resultant papermaterial was impregnated with an acrylic emulsion dispersed with ananionic emulsifier containing a sulfonate (available from Rohm and HassCo. Ltd. under the trade name “PrimalTR-934HS”) in an amount of 10 g/m²expressed in terms of solid content as the dry paper strengthening agentat the time of paper making with a size press coater.

[0062] As a result, there was obtained electroconductive paper which hada basis weight, of 300 g/m², and the physical properties of which aregiven in Table 1.

COMPARATIVE EXAMPLE 3

[0063] A sheet was prepared from a paper material prepared by adding to100 parts by weight of wood pulp (N-BKP/L-BKP ratio by weight being20/80), 0.5 part by weight expressed in terms of solid content, ofepoxidized polyamide resin (available from Japan PMC Co. Ltd. under thetrade name “WS-570”) as the wet paper strengthening agent; and 0.5 partby weight expressed in terms of solid content, of polystyrene resin(available from Seiko Chemical Industries Co. Ltd. under the trade name“Pearl Gum CS”) as the sizing agent. The resultant paper material wascoated on both sides thereof in an amount of 3 g/m² expressed in termsof solid content with oxidized starch (available from Oji Corn StarchCo. Ltd. under the trade name “Oji Ace A”) as the surface strengtheningagent at the time of paper making with a size press coater. As a result,there was obtained paper which was free from any electroconductivesubstance and had a basis weight of 300 g/m², and the physicalproperties of which are given in Table 1. TABLE 1 Sulfate Half-time ionsperiod Corrosion Surface extracted of static test Surface resistivityamount electricity (color pH (Ω) (ppm) (sec) change) Example 1 6.0 1.1 ×10³ 0.753 0.12 none Example 2 6.2 7.5 × 10² 0.482 0.14 none Example 36.0 1.1 × 10⁴ 0.679 0.11 none Comparative 4.6 1.5 × 10³ 6.262 0.12 yesExample 1 Comparative 4.6 1.7 × 10³ 1.855 0.11 yes Example 2 Comparative6.1  1.0 × 10¹⁰ 0.523 0.35 yes Example 3

What is claimed is:
 1. Electroconductive paper which comprises on atleast one side thereof, an electroconductive-substance-containing layerhaving a surface resistivity of at most 10⁷ Ω and a surface pH in therange of 5.5 to 8.0.
 2. The electroconductive paper according to claim1, which has a half-life period of static electricity being at most 0.2second.
 3. The electroconductive paper according to claim 1, wherein theconcentration of sulfate ions thereof is at most 1 ppm, which areextracted by subjecting 1 g of electroconductive paper to an extractiontreatment in 70 milliliter (mL) of deionized water at 100° C. for 1hour.
 4. The electroconductive paper according to claim 2, wherein theconcentration of sulfate ions thereof is at most 1 ppm, which areextracted by subjecting 1 g of electroconductive paper to an extractiontreatment in 70 mL of deionized water at 100° C. for 1 hour.
 5. Acarrier for an electronic member which carrier makes use of theelectroconductive paper as set forth in claim
 1. 6. A carrier for anelectronic member which carrier makes use of the electroconductive paperas set forth in claim
 2. 7. A carrier for an electronic member whichcarrier makes use of the electroconductive paper as set forth in claim3.